Makes sense. Academics always discount the intelligence of past people.
People seem to naturally pledge loyalty and do favors for each other, it makes sense that “debt” would be a primary medium of exchange.
If anything, barter is more complex than a promise, as without money how do you evaluate the value of a sheep vs a bunch of grain or some service? Is building a wall worth more or less than sex? How do the two match up against the sheep? How do you trade for fractional value?
The big difference innovation was the organized trading of debt and shares of enterprises a couple hundred years ago. The rest is probably been a thing since cavemen.